An ammunition case trimmer, components thereof, and associated methods. The ammunition case trimmer includes a shroud and a cutter. The cutter is supported in the shroud by at least one rotational bearing. The shroud defines a case guide for receiving the case and guiding the case into engagement with a cutting head of the cutter. The shroud is rotatable with respect to the cutter about the axis of rotation. A proximal free end of the cutter is arranged with respect to the shroud to permit reception of the proximal free end in a chuck of a drill.